Organic Light-Emitting diode (OLED) has been frequently used in the flat panel display device more and more recently due to its thinness contour and lightness, wide viewing angle, high response speed, high contrast and other advantages.
With the development of display technology, currently there occurs a method for an OLED display device to realize a full-color display by combining a color conversion material with blue light emission. The OLED at least includes an anode, a light-emitting layer and a cathode, and the light-emitting layer is generally made of an organic material. A feasible method for realizing the full-color display by combining the color conversion and the blue light emission is to use an inorganic doped material, such as Ce doped yttrium aluminum garnet, Eu doped alkaline earth metal silicate, or rare earth doped silicon nitride or oxynitride, which can be stimulated by the blue light. However, these color conversion materials usually have problems of low color purity and low efficiency.
With the development of material technology, currently some people have proposed the use of quantum dots (a nanostructure) as a color conversion material. Quantum dots are generally light-emitting particles of nanometer sizes, and emit visible fluorescence after being stimulated by absorbing certain energy. The quantum dots can be precisely controlled to emit light of different wavelengths simply by replacing chemical composition of the quantum dots or adjusting the sizes of the quantum dots, so as to get the visible light of different colors; compared to the traditional color conversion material, both intensity and stability of fluorescence emitted from the quantum dots are good, furthermore, the quantum dots have high luminous efficiency, narrow half peak width of the luminous spectrum, and high color purity, therefore, the quantum dots are an excellent color conversion material.
FIG. 1 shows a schematic view of a structure of an organic light-emitting diode: the organic light-emitting diode 20 includes a first electrode 21, a second electrode 25, and an electron transporting layer 22, a light-emitting layer 23 (blue OLED or ultraviolet OLED) and a hole transporting layer 24 provided between the first electrode 21 and the second electrode 25; a quantum dot layer 26 is provided outside the organic light-emitting diode 20, namely the quantum dot layer 26 is provided above the second electrode 25. There are a plurality of quantum dot units 280 uniformly distributed inside the quantum dot layer 26; red light quantum dots and green light quantum dots correspond to red sub-pixel units and green sub-pixel units, respectively; a color filter 27 is used for filtering out blue light or ultraviolet light emitted from the quantum dot layer 26, improving the color purity.
It can be found that, when manufacturing the OLED shown in FIG. 1, two additional (for blue OLED) or three additional (for ultraviolet OLED) masks are required for the quantum dot layer 26; on the one hand, the cost is increased, and on the other hand, the manufacturing procedure is complex.